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7 The voyage of the Beagle convinced Darwin that 1.Members of the same species often change slightly in appearance after becoming geographically isolated from each other 2.Organisms living on oceanic islands often resemble organisms found living on a close mainland 3.Factors other than or in addition to climate play a role in the development of plant and animal diversity 4.Organisms of the past and present are related to one another (but there are no fossils in the Galapagos)

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8 "The distribution of the tenants of this archipelago would not be nearly so wonderful, if, for instance, one island had a mocking-thrush, and a second island some other quite distinct genus.... But it is the circumstance, that several of the islands possess their own species of tortoise, mocking- thrush, finches and numerous plants, these species having the same general habits, occupying analogous situations, and obviously filling the same place in the natural economy of this archipelago, that strikes me with wonder...." Darwin, The Voyage of the Beagle

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10 Finch family tree based on a 660-nt sequence Molecular Biology and Evolution 18: (2001).01 change per position Darwin’s Galapagos finches

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11 Blue-Footed Booby (Ben Lester) Red-Footed Booby

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12 Masked booby A recently discovered a behavior, called siblicide, occurs among booby chicks. The larger chick always kills the younger chick, sometimes aided by the parents. Scholars debate the selective advantage of such behavior. Perhaps the parents succeed better by insuring the survival of at least one chick.

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13 Male Frigate Bird Displaying no oil on feathers cannot land on water steals other birds’ fish

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14 Galapagos Waved Albatrosses in Courtship 2 m wingspan

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15 Video of Galapagos Waved Albatrosses in Courtship

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16 photo by Ben Lester Female Albatross on the nest

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17 photo by Ben Lester

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18 The Galapagos tortoises reach sexual maturity at the age of 40 and have clutches of eggs. Eggs hatch at d.

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19 Galapagos Penguins World’s Northernmost population of penguins. After "El Nino" in 1983 the population decreased from 12,000 to just 2,000 birds.

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20 Marine Iguanas

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21 Marine Iguana feeding Marine iguanas feed once a day. The mature lizards swim out through the tidepools to dive to the bottom for algae; smaller iguanas feed off the rocks in the tidal zone. An iguana may lose up to 10 degrees C of body temperature on these feeding missions. Because they are cold-blooded ("ectothermic"), iguanas must bask on the hot lava rocks throughout the day until they raise their internal temperature.

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22 The increased rainfall that accompanies El Niño results in greater food availability for most terrestrial organisms in the Galápagos, but marine life generally suffers from the higher water temperature, which decreases the amount of dissolved oxygen. Green and red algal species, which are the marine iguanas' preferred food, disappear and are replaced in intertidal areas by brown algae which iguanas find hard to digest. Up to 90% of marine iguana populations on islands can die of starvation as a result of these environmental changes. During a recent El Niño event (1997–98), larger individuals of the two island populations shrank more than smaller individuals. The scale of the shrinkage — up to 20% of body length — means that it cannot simply be explained by decreases in cartilage and connective tissue, which together make up only 10% of total body length. Apparently bone absorption accounts for much of the reduction.

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45 Diving mammals have much higher: blood volume hemoglobin concentration and especially myoglobin than other mammals. More than 80% of the oxygen is in the blood and muscle. two oxygen-carrying heme proteins

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46 Diving mammals have much higher: blood volume hemoglobin concentration and especially myoglobin than other mammals. More than 80% of the oxygen is in the blood and muscle. two oxygen-carrying heme proteins

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47 lens detachable CCD camera 8 mm tape recorder Ti or Al housing batteries and computer fins float transmitter 35 cm 900 nm LEDs Audio channels (1) accelerometer (2) microphone Transducers for pressure, water speed, and compass bearing are sampled once per second, and the data are stored on a PCMCIA card. A separate housing (17 cm long and 5.5 cm in diameter) for the gimbaled flux-gate compass is positioned behind the main housing and connected to it with a cable. Crittercam (UC Santa Cruz)

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53 “Lungs are a liability for deep divers because, in contrast to muscle and blood, they are a better nitrogen store than oxygen store.” Some compressed air remains in the windpipes, but a collagen lining prevents absorption by the blood “The early occurrence of lung collapse in seals makes the lung almost useless as an O 2 store, whereas it limits N 2 absorption during the dive.” a. flexible chest; b. no collagen in the smallest branches complete peripheral collapse at m Diving mammals don’t get the bends: adaptations to pressure

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59 Darwin, The Voyage of the BeagleThe Voyage of the Beagle Darwin, The Origin of SpeciesThe Origin of Species Michael Jackson, Galapagos, University of Calgary Press, 1994 Jonathan Weiner, The Beak of the Finch: a Story of Evolution in our Time, Knopf, 1995